Notes on the vocalizations of White-fringed Antwren (Formicivora grisea)

In the following we briefly analyze and compare voice of the different races of White-fringed Antwren (Formicivora grisea). We also try to quantify the extent of any vocal differences using the criteria proposed by Tobias et al. (2010), as a support for any taxonomic review. We have made use of sound recordings available on-line from Xeno Canto (XC) and Macaulay Library (ML).

The difference in vocalization between 'Northern' and 'Southern' White-fringed Antwren was e.g. discussed in Hilty (2003), but is decidedly more complex than suggested there.

In fact, all races have a comparable 'song' which consists of a single 'note', which is repeated for shorter or longer periods:

hondae: repeated note has the shape of a small letter 'n'

pace

0.17-0.25

top frequency

2100-2500Hz

note length

0.07-0.09s

freq. range

1100-1300Hz

fumosa: repeated note has the shape of a small letter' n'

pace

0.16-0.22

top frequency

1900-2000Hz

note length

0.06-0.07s

freq. range

1000-1100Hz

intermedia: repeated note has the shape of a small letter 'n' or 'h' (often only a few notes repeated)

pace

0.15-0.17

top frequency

2200-3000Hz

note length

0.06-0.07s

freq. range

1100-1800Hz

orenocensis: repeated note has the shape of a small letter 'h'

pace

0.14-0.15

top frequency

2900-3200Hz

note length

0.04-0.05s

freq. range

1300-1600Hz

tobagensis: repeated note has the shape of a small letter 'n'

pace

0.22

top frequency

2500-2700Hz

note length

0.06s

freq. range

1100-1200Hz

rufiventris repeated 'note' has the shape of a very long 'h' and preceded by a short sharply downslurred note (inaudible by human ear)

pace

0.29-0.32

top frequency

3600-3900Hz

note length

0.04-0.07s

freq. range

2600-3000Hz

grisea: repeated 'note' has the shape of a sharply falling line, barely recognizable as an 'h' and preceded by a short sharply downslurred note or more complex shape (inaudible by human ear)

pace

0.31-0.46

top frequency

3200-4400Hz

note length

0.06-0.08s

freq. range

2500-3400Hz

when grouping the above taxa into two groups (Southern = rufiventris/grisea and Northern: other races) and combining data we get:

'Northern' White-fringed Antwren (n>10)

repeated note has the shape of a small letter 'n' or 'h'

pace

0.14-0.25

top frequency

1900-3200Hz

note length

0.04-0.09s

freq. range

1000-1800Hz

'Southern' White-fringed Antwren (n>10)

repeated note has the shape of a sharply falling line, somewhat like an 'h' and preceded by a short sharply downslurred note or more complex shape (inaudible by human ear)

pace

0.29-0.46

top frequency

3200-4400Hz

note length

0.04-0.08s

freq. range

2500-3400Hz

The main vocal differences between the two groups are thus frequency range and top frequency of repeated notes (score 2 or 3) and pace (score 1 or 2), leading to a total score of about 4.

Besides this 'song', there are other clear differences in voice. E.g., a very distinct vocalization is 'a long whistle followed by a trill'. This has been documented for hondae, intermedia and orenocensis, and would thus seem unique for 'Northern White-fringed Antwren'. Possibly there are more differences to be found when analyzing the complete vocabulary.

As a final remark, there is no info about albicincta, other than a description like 'repeated chup notes'

This note was finalized on 6th May 2015, using sound recordings available on-line at that moment. We would like to thank in particular the many sound recordists who placed their material on XC and ML.